[PATCH 28/50] drm: Remove DRM_WAIT_ON from all drivers

Thomas Hellstrom thellstrom at vmware.com
Wed Dec 18 01:37:54 PST 2013


On 12/18/2013 09:25 AM, Daniel Vetter wrote:
> On Wed, Dec 18, 2013 at 11:39:27AM +1000, Dave Airlie wrote:
>> On Wed, Dec 11, 2013 at 8:34 PM, Daniel Vetter <daniel.vetter at ffwll.ch> wrote:
>>> Since this is all old ums stuff (including the one in the radeon
>>> driver) I've just tried to perfectly replicate the existing semantics.
>>>
>>> Reinventing wait queue code with semantics that differ from all the
>>> standard linux wait functions is just hairy, so now we can get rid of
>>> this and so make sure it'll never again be used.
>>>
>>> Oh and: via futexes ... *shudder*
>> This one worries me, I've had numerous attempts to rip this out in the
>> past and they always changed semantics on some devices and broke
>> stuff.
>>
>> The sneaky timeout is essential for a lot of the hardware
>>
>> https://urldefense.proofpoint.com/v1/url?u=http://marc.info/?l%3Ddri-devel%26m%3D111383274225047%26w%3D1&k=oIvRg1%2BdGAgOoM1BIlLLqw%3D%3D%0A&r=l5Ago9ekmVFZ3c4M6eauqrJWGwjf6fTb%2BP3CxbBFkVM%3D%0A&m=wgfMdGK1q8n48mRclOyEBEeb4OB1u5PwhRxswGxwjGY%3D%0A&s=6e87c42702c679927c4e0fab27ef8874b2a22707cb860f0de000df4798199e63
>>
>> So I think I'd like a few more people to review this one before I go
>> near it again :-)
> Oh, and I've thought the only tricky stuff is mapping the errno's
> correctly. I think if we have such cases of racy drivers then the right
> thing to do is to shovel this macro into drivers and slap a big comment
> about signalling races on top of that code.
>
> Thomas report doesn't say so, but I guess it's for via. Thomas, do you
> still have a vague recollection of what this has been about?

Yes, this was with via, but IIRC there were other drivers affected as well,
but OTOH, I think the kernel wait code was fixed for races some time
after that....

/Thomas





>
> Dave, do you want me to just respin this one with via left as-is (and the
> macro pushed into the via driver)?
>
> Thanks, Daniel


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